From patchwork Mon Nov 14 18:27:05 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krzysztof Kozlowski X-Patchwork-Id: 9428171 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 82B21602F0 for ; Mon, 14 Nov 2016 18:27:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 788A228ABD for ; Mon, 14 Nov 2016 18:27:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6D29228ABF; Mon, 14 Nov 2016 18:27:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2EFD428ABE for ; Mon, 14 Nov 2016 18:27:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935893AbcKNS1e (ORCPT ); Mon, 14 Nov 2016 13:27:34 -0500 Received: from mail.kernel.org ([198.145.29.136]:49572 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934371AbcKNS1c (ORCPT ); Mon, 14 Nov 2016 13:27:32 -0500 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D0ABF2024C; Mon, 14 Nov 2016 18:27:25 +0000 (UTC) Received: from localhost.localdomain (bzq-79-178-158-20.red.bezeqint.net [79.178.158.20]) (using TLSv1.2 with cipher AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2274E20259; Mon, 14 Nov 2016 18:27:19 +0000 (UTC) From: Krzysztof Kozlowski To: Russell King , Kukjin Kim , Krzysztof Kozlowski , Javier Martinez Canillas , linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Ben Dooks , Lee Jones , Arnd Bergmann , Marek Szyprowski , Bartlomiej Zolnierkiewicz , Sylwester Nawrocki , Tomasz Figa Subject: [PATCH] ARM: Drop fixed 200 Hz timer requirement from Exynos platforms Date: Mon, 14 Nov 2016 20:27:05 +0200 Message-Id: <1479148025-469-1-git-send-email-krzk@kernel.org> X-Mailer: git-send-email 2.7.4 X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP All Samsung platforms, including the Exynos, are selecting HZ_FIXED with 200 Hz. Unfortunately in case of multiplatform image this affects also other platforms when Exynos is selected. This looks like an very old legacy code, dating back to initial upstreaming of S3C24xx. Probably it was required for s3c24xx timer driver, which was removed in commit ad38bdd15d5b ("ARM: SAMSUNG: Remove unused plat-samsung/time.c"). Since then, this fixed 200 Hz spread everywhere, including out-of-tree Samsung kernels (SoC vendor's and Tizen's). I believe this choice was rather an effect of coincidence instead of conscious choice. In fact Exynos can work with different timers. Few perf mem and sched tests on Odroid XU3 board (Exynos5422, 4x Cortex A7, 4x Cortex A15) show no regressions when switching from 200 Hz to other values. Reported-by: Lee Jones Reported-by: Arnd Bergmann Signed-off-by: Krzysztof Kozlowski Tested-by: Javier Martinez Canillas --- Testing on other Exynos platforms would be appreciated. --- arch/arm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index b5d529fdffab..0d10e45f9175 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1497,7 +1497,7 @@ source kernel/Kconfig.preempt config HZ_FIXED int default 200 if ARCH_EBSA110 || ARCH_S3C24XX || \ - ARCH_S5PV210 || ARCH_EXYNOS4 + ARCH_S5PV210 default 128 if SOC_AT91RM9200 default 0